1. Field of the Invention
The present invention relates to an electronic module and a method of manufacturing the electronic module.
2. Description of the Related Art
An electronic module which functions as a part of an electronic device is known. Such an electronic module is mounted on an electronic device to have a predetermined function which is a part of that of the electronic device. For example, the electronic module may be a high-frequency module (radio frequency module) which has a communication function, capable of sending and receiving signals, of a communication device such as a mobile phone or the like in a radio communication device field.
As such an electronic module is used when mounted on the electronic device, the size of the electronic module is determined based on the size of the electronic device. When the electronic device is small, it is necessary to make the electronic module small as well.
Conventionally, when it is necessary to shield the electronic module, as for the case of the high-frequency module, the electronic module is housed in a metal shield case. However, it is necessary to ground the metal shield case by a ground pattern formed in a substrate on which the electronic module is mounted. Thus, in order to electrically connect the metal shield case with the ground pattern in the substrate, it is necessary to connect the metal shield case by a solder bump formed on a land formed at an upper surface of the substrate. Thus, it is necessary to form the land on the upper surface of the substrate within the metal shield case. This land may become larger as it is used for the largest component in the electronic module, so that the shield case needs also be made larger to accommodate the land.
Further, as the shield case is made of a conductive material, it is necessary to have enough space between the metal shield case and an outer case, which covers the entirety of the electronic component including the metal shield case. Thus, a dead zone is increased, thereby increasing the size of the electronic component. Further, as a shortage between the metal shield case and the upper electrode components formed at the upper surface of the substrate may occur, enough clearance is necessary to further increase the dead space.
Further, it is necessary for the shield case to have a thickness of at least about 100 μm in order to compose the electronic module, the size of the electronic module becomes larger at this point as well.
A module component without such a shield case is provided. The module component includes a circuit substrate on which an electronic component is mounted, a sealing body which seals the electronic component by a first resin, having a size the same as the circuit substrate and provided with a groove so that a ground pattern in the circuit substrate can be exposed from a bottom or side surface of the groove, a metal film which covers the upper and side surfaces of the sealing body and the circuit substrate by electroless plating and electroplating to be connected to the ground pattern in the substrate at the bottom or side surface of the groove, and a second resin which fills the groove (see Patent Document 1).
However, according to the conventional method disclosed in Patent Document 1, the metal film is formed using two different wet processes including a first process of forming a copper metal film by electroless plating and a second process of forming a dense metal film by electroplating. Thus, larger apparatuses are necessary for each of the wet processes and the manufacturing cost becomes high. It means that the sealing body which is made of resin is an insulating body and it is impossible to directly form a metal layer on the insulating body by electroplating. Thus, it is necessary to form a seed metal film on the insulating body by electroless plating, and then electroplating is performed using the seed metal film. Therefore, the two steps are necessary and the two kinds of apparatuses are necessary for the two steps, which increases the manufacturing cost.
Further, in both of the electroless plating and the electroplating, it is necessary to dip the sealing body with the circuit substrate in plating solutions, so that unnecessary metal film may be formed at a back side surface of the circuit substrate. Thus, a step of removing such an unnecessary metal film is further necessary.